Question: $J$ $K$ $L$ If: $ JK = 3x + 5$, $ KL = 4x + 7$, and $ JL = 19$, Find $KL$.
Answer: From the diagram, we can see that the total length of ${JL}$ is the sum of ${JK}$ and ${KL}$ $ {JK} + {KL} = {JL}$ Substitute in the expressions that were given for each length: $ {3x + 5} + {4x + 7} = {19}$ Combine like terms: $ 7x + 12 = {19}$ Subtract $12$ from both sides: $ 7x = 7$ Divide both sides by $7$ to find $x$ $ x = 1$ Substitute $1$ for $x$ in the expression that was given for $KL$ $ KL = 4({1}) + 7$ Simplify: $ {KL = 4 + 7}$ Simplify to find ${KL}$ : $ {KL = 11}$